Don 't bother me with facts
As they put it, "A parent's story about her son deteriorated after receiving the MMR vaccine and her expressed belief that the vaccine caused her son's autism is compelling, memorable, and hard to dismiss from our thoughts. Even in the face of overwhelming scientific evidence and statistics culled from studies of hundreds of thousand of people, that one personalized case carries undue influence." (p. 178) The mother her was Jenny McCathy, an actress who broadcast her point of view on The Oprah Winfrey Show. As a result of so many people buying into this theory, many children were not immunized and contracted the measles.
So we have the belief of an celebrity model/actress versus that of science, and people will go with the former. Today I saw a posting on one of the shul lists that said: "I am looking for a Pediatrician who doesn't impose vaccinations. ...Please only respond with a name of a doctor. I do not want to receive anyone else's opinions or comments on vaccinations. I am very well read on this issue."
In other word, "I'm certain I'm right and don't want to be bothered with facts that could show how I am endangering my own child and others." This is not just a matter of personal choice, for it has ramifications for the health of others. The reason we have heard of measles cases spreading in the US is because so many parents have decided not to immunize their children. You may wonder, why not consults experts? No, instead the parent wants to go with his/her sense of what is right.
It just happens to be that that instinct is dead wrong -- both scientifically and halachically. Here is Rabbi Avinar's response to the question of immunization: :Vaccinations
Q: Should we have our children vaccinated? People mention that there are risks involved.A: The chances of side-effects are extremely low compared to the hundreds of millions of child who receive vaccinations. In life-threatening situations we follow the majority, and all the more so when the minority of cases is (numerically) negligible.